Measuring the strength of concrete: Sensors vs Cube test

When it comes to ascertaining the strength of concrete, professionals have two primary methods at their disposal: compression testing of concrete cubes and utilising embedded sensors. Both approaches come with their unique pros and cons. 

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This article offers a balanced comparison of these two techniques, aiming to provide clarity on which method suits various construction circumstances.

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Read more: We make comparisons between cube testing and cylinder testing and explain three methods for measuring concrete maturity.

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Concrete Cube Testing: A Conventional Approach

Concrete cube testing, following the British standard, is a conventional technique widely adopted in the UK and globally. This method involves creating sample cubes from the concrete mix, which are then subjected to a compressive force using a specialised machine. The result provides an indicative measure of the concrete's strength.

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Pros of Cube Testing

1. Concrete Cube Testing is British Standard: Compliance with the British standard (BS EN 12390) ensures rigorous testing and quality assurance.
2. Simplicity: It is a straightforward and easy-to-understand method.

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Cons of Cube Testing

1. Time-Consuming: The curing process for test cubes can take up to 28 days.
2. Indicative Rather Than Representative: The strength derived from cube tests is often an average, not necessarily indicative of the strength of the whole concrete structure.
3. Data point are given at fixed intervals rather than real-time

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Sensors: The Modern Method

A more contemporary approach to assess concrete's strength is the application of sensor technology. These sensors, embedded within the concrete structure, gather real-time data about the concrete's strength, temperature, and moisture levels.

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Pros of Using Sensors

1. Real-Time Data: Sensors provide immediate, real-time strength measurements, aiding in efficient project management.
2. Accuracy: As sensors are embedded within the actual structure, they offer an accurate representation of the whole concrete's strength.
3. Reflective of in-situ strength: In-situ measurements might cure sooner than lab results due to increased temperatures compared to the controlled environment of the lab.

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Cons of Using Sensors

1. Cost: Sensors can add to the project's initial costs, especially for smaller projects. For larger projects the cost might not be as significant when compared to the money saved by being accurate and time efficient. 

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Read more: We explain the differences between in-situ concrete and lab cured concrete and  Can you trust the maturity method?

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Cube Testing vs Sensors: The Verdict

Choosing between cube testing and using sensors often depends on the project specifics, like size, budget, and time constraints. While the traditional compression testing of concrete cubes offers a simple, standardised method, sensor technology promises real-time data and increased accuracy.

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In an ideal world, using both in conjunction might provide the most comprehensive picture of concrete strength. The cube test could serve as an initial strength indicator, while sensors could monitor the concrete's strength evolution over time. 

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As construction technology continues to advance, the synergy of these two methods might become the new norm, ensuring concrete structures of the highest strength and integrity.

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However, sensors are most beneficial on projects where load bearing activities on concrete are on the critical path. Mainly because the real-time data allows people to take action as quickly as possible saving vast amounts of time.

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Remember, the choice of method always comes down to what best fits your specific construction scenario. Here's to stronger, safer, and more efficient construction practices!

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How do wireless sensors measure the strength of concrete?

Our wireless, cast-in-place concrete sensors, measure and record the temperature and within the concrete in real-time. These sensors relay the data wirelessly to a nearby hub that collects data from all sensors deployed in the vicinity.

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The data is used to calculate the strength of the concrete based on the maturity method. The maturity method is a principle based on the fact that concrete gains strength with time and temperature. By knowing the concrete mix’s specific strength gain relationship with time and temperature (usually supplied by the mix provider), it is possible to calculate the in-place strength of the concrete in real-time.

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The collected data is then transmitted to a cloud-based platform, ConcreteDNA which allows engineers and construction teams to view and analyze the data in real-time. 

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Read more: We explain the maturity curve and How using sensors improves the measuring of concrete maturity.

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Frequently asked questions

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Are sensors intrusive to the structure of the concrete?

Modern concrete sensors are designed to be unobtrusive and do not compromise the structural integrity of the concrete. They are usually embedded at the time of concrete placement.

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Can I use both cube testing and sensors on the same project?

Absolutely! Using both methods can provide a comprehensive understanding of the concrete's strength. Cube testing provides an initial quality check, and sensor data can track the concrete's strength development over time.

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What does the concrete cube testing British standard entail?

The British standard BS EN 12390 outlines procedures for making, curing and testing concrete cubes for compressive strength. It specifies details such as the shape, size, material, and curing conditions of the test samples.